Lecture15 - ExistenceofLife .Arewealone? thatharborslife? (...

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Any other important feature of Earth? Existence of Life   This makes us unique so far.  Are we alone?  Are there other places in the solar system  that harbors life?  Is there any other place in the Universe that harbors life? The Existence of Intelligent Life   (though world events of late make one wonder) Brief History of the Earth: Planet formed from rocky debris, part of formation of the Sun.  Planetesimals  coalesced, bombarding surface, heating it. Further heating caused by internal  radioactivity eventually  melting it.  Entire planet once largely molten, allowed heavier elements (Iron, Nickel) to  sink and form  differentiated  core. Light materials floated up from interior.  Crust formed, cracked, allowing volcanoes to flood.   Internal heating causes  lithosphere to move around and produce plate tectonics.  Water from comets? Much oxygen from billions of years of plant life.
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Lecture15 - ExistenceofLife .Arewealone? thatharborslife? (...

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